1ea9
From Proteopedia
Cyclomaltodextrinase
Structural highlights
FunctionCDAS_BACSP Hydrolyzes alpha-, beta- and gamma-cyclodextrins and the resulting linear maltodextrins, with the highest activity with beta-cyclodextrin (cyclomaltoheptaose). Soluble starch is hydrolyzed slowly, but it is nevertheless preferred over pullulan as a substrate. Is able to hydrolyze amylose and amylopectin, with a very strong preference for amylose, with maltose and glucose as the main products (PubMed:9606956, PubMed:10620329, PubMed:16536613). Maltose and glucose are the main hydrolysis products of cyclomaltodextrins, maltodextrins and starch, whereas panose is the main hydrolysis product of pullulan. Acarbose is partially hydrolyzed to glucose and pseudotrisaccharide. No activity with maltose as substrate (PubMed:9606956, PubMed:10620329). Has transglycosylating activity with high concentrations of maltotriose, maltotetraose and starch (PubMed:9606956).[1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedOver 20 enzymes denoted as cyclomaltodextrinase, maltogenic amylase, or neopullulanase that share 40-86% sequence identity with each other are found in public data bases. These enzymes are distinguished from typical alpha-amylases by containing a novel N-terminal domain and exhibiting preferential substrate specificities for cyclomaltodextrins (CDs) over starch. In this research field, a great deal of confusion exists regarding the features distinguishing the three groups of enzymes from one another. Although a different enzyme code has been assigned to each of the three different enzyme names, even a single differentiating enzymatic property has not been documented in the literature. On the other hand, an outstanding question related to this issue concerns the structural basis for the preference of these enzymes for CDs. To clarify the confusion and to address this question, we have determined the structures of two enzymes, one from alkalophilic Bacillus sp. I-5 and named cyclomaltodextrinase and the other from a Thermus species and named maltogenic amylase. The structure of the Bacillus enzyme reveals a dodecameric assembly composed of six copies of the dimer, which is the structural and functional unit of the Thermus enzyme and an enzyme named neopullulanase. The structure of the Thermus enzyme in complex with beta-CD led to the conclusion that Trp47, a well conserved N-terminal domain residue, contributes greatly to the preference for beta-CD. The common dimer formation through the novel N-terminal domain, which contributes to the preference for CDs by lining the active-site cavity, convincingly indicates that the three groups of enzymes are not different enough to preserve the different names and enzyme codes. Cyclomaltodextrinase, neopullulanase, and maltogenic amylase are nearly indistinguishable from each other.,Lee HS, Kim MS, Cho HS, Kim JI, Kim TJ, Choi JH, Park C, Lee HS, Oh BH, Park KH J Biol Chem. 2002 Jun 14;277(24):21891-7. Epub 2002 Mar 28. PMID:11923309[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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